ABC News(NEW YORK) -- An off-duty undercover New York City cop was officially charged Wednesday for his alleged role in the assault of an SUV driver while the police detective was part of a group motorcycle ride.

Undercover narcotics officer Wojciech Braszczok, 32, was charged with gang assault, assault and criminal mischief in connection with the attack on SUV driver Alexian Lien on Sept. 29. Those charges include felonies -- upgraded from the initial misdemeanor charges of riot and criminal mischief announced by authorities when he was arrested Tuesday.

Braszczok's attorney John Arlia called the gang assault charge an "absolute overcharge" and said there's no evidence the detective knew the other bikers. The riders are a loosely knit group that arranges rides via the Internet, Arlia said.

During his appearance in Manhattan's criminal court, Braszczok wore army fatigues and a black hooded sweatshirt. He stood motionless as the charges were read.

Braszczok initially told his superiors days after the incident that he saw the attack but did not stop it for fear of blowing his cover, police said. But video captured at the scene revealed that he actually participated by smashing the back window of Lien's Range Rover, law enforcement sources said.

Braszczok's attorney said his client is accused of breaking "what was already broken." There was a "gaping softball [-sized] hole" in the window that the detective is accused of breaking, Arlia said during the court appearance.

While Braszczok is not accused of directly assaulting Lien, prosecutors said he terrorized the driver's family. He was captured on video kicking the passenger-side rear door multiple times where, prosecutors pointed out, Lien's 2-year-old daughter was in the back seat.

Braszczok is the latest in a string of arrests connected to the incident. Five other motorcyclists have been charged, and police say they are continuing to search for suspects.

The melee began around 2 p.m. on Sunday, Sept. 29, when Lien, who was driving on the highway with his wife and 2-year-old daughter on an outing to celebrate the couple's wedding anniversary, tapped the back of a motorcycle that cut in front of him and slowed down, police said. The rest of the bikers then closed in on him, prompting Lien to speed off, hitting three bikers as he accelerated away from the group, according to the NYPD.

The group chased Lien and then pulled him from his car and beat him, cops said.

Police released photos of additional suspects to the public on Tuesday.

Braszczok is being held on $100,000 cash bail or $150,000 bond. He is a 10-year veteran of the NYPD, according to a law enforcement source. He is an undercover detective who spent much of his police career in narcotics but recently transferred to another division, the source said.

Investigators believe that while Braszczok was one of three cops on the ride in the general area of the attack, he was the closest to the beating and the only one to have a clear view of what was happening, a law enforcement source said. They believe another detective was further away from the attack and a third, an officer, was "in the way back" of the motorcycle pack, the source said. The other two officers' conduct was being probed, but investigators said they were not expected to face criminal charges, the source added.

Internal Affairs had been reviewing Braszczok's former narcotics cases as charges against him were being contemplated, the source added.

Clint Caldwell, 32, was also expected to be arraigned Wednesday for his role in allegedly helping to pull Lien out of the SUV and beat him.

"In the last few days, serious charges have been brought against several defendants in last Sunday's attack," Erin Duggan, a spokeswoman for Manhattan District Attorney Cyrus Vance, said Tuesday. "As we said from the beginning of the investigation, the NYPD and the district attorney's office are methodically scrutinizing the evidence to build the strongest possible cases in our continuing effort to hold accountable those responsible."

Much of the chase was caught on a helmet camera video that was then uploaded to the Internet. Police said they have used the video and images taken at the scene to identify suspects. Detectives have also obtained additional footage and photographs from others that have helped them piece together what went on, sources said.

A grand jury is already hearing evidence in the assault cases that have been filed, and Lien is expected to make a video statement for prosecutors for the grand jury, authorities said.